Since his diagnosis with Alzheimer's in 2007, beloved fantasy author Terry Pratchett has kept up his rigorous writing and touring schedule, despite his growing health difficulties. These days, he writes entirely with the help of voice-activated software and his assistant Rob Wilkins. Now he's done an extensive interview with New Statesman's Laurie Penny, where he reveals what his life is like now, and what's coming next for Discworld.

He has lost the ability to use a keyboard altogether and can do very little with a pen. His most recent four books have been written entirely by dictation, and with the help of his assistant of 12 years, Rob Wilkins.

"I can no longer type, so I use TalkingPoint and Dragon Dictate," Pratchett says, as Rob drives us to the café in a rather unexpected large gold Jaguar. "It's a speech-to-text program," he explains, "and there's an add-on for talking which some guys came up with."

Pratchett also said that he's thinking about the future of the Discworld series, and his daughter Rhianna is going to take the helm when the author can no longer write. The younger Pratchett already has writing chops — she's written for a number of videogames, including Tomb Raider, Prince of Persia, Overlord, and Heavenly Sword (for which she won an award). Writes Penny:

[Rhianna] will be a co-writer on the BBC Discworld series The Watch, news of which has had fans like me chewing their cheeks in excitement. Mine may never recover after hearing some particularly exciting casting details that I'm absolutely not allowed to tell you about.

Run by Pratchett's new production company, Narrativia, The Watch will continue the well-loved City Watch saga where the books left off, and Rhianna will be an important member of the writing team. The author tells me that he will be happy for her to continue writing the Discworld books when he is no longer able to do so. "The Discworld is safe in my daughter's hands," Pratchett assures me.

Rhianna has grown up immersed in her father's universe and knows it inside out. Listening to him talking about his daughter, I realise it is the first time I've heard him acknowledge the possibility of not being able to write any more.

It will be interesting to see how the next chapters in Pratchett's incredible life — and his much-adored Discworld series — unfold.